Heat transfer coil

ABSTRACT

Heating coil construction with compact arrangement of headers and pipes, and shaping of the pipes so that leak proof attachment of the pipe ends in the headers is easily achieved and internal drainage of heating fluid is obtained for all pipes and headers. The construction is designed for easy repair in the field if leaks occur.

United States Patent 1191 Babunovic et al.

1 1 Aug. 5, 1975 1 1 HEAT TRANSFER COIL [751 Inventors: Momir Babunovic, Des Peres; Harry J. Wiskoski, Florissant, both of M0.

[73] Assignee: Barry-Wehmiller Company, St.

Louis, Mo.

[22] Filed: Aug. 3, 1973 [21] Appl. No: 385,432

[52] U.S. Cl. H 165/175; 29/1574; 134/107; 165/178 [51] Int. Cl .4 F28f 9/18 [58] Field of SearchuHm... 165/117, 173, 175.178, 165/128, 176; 29/1574; 134/105, 107, 108

[561 References Cited UNITED STATES PATENTS 2.733.899 2/1956 Lehmunn 165/176 X FOREIGN PATENTS OR APPLICATIONS 263,093 3/1927 United Kingdom 11 165/117 United Kingdom 165/128 United Kingdom 165/178 Primary Examiner-Albert W. Davis, Jr Assistant Examiner--She1d0n Richter Attorney, Agent or Firm-Gravely, Lieder & Woodruff ABSTRACT Heating coil construction with compact arrangement of headers and pipes, and shaping of the pipes so that leak proof attachment of the pipe ends in the headers is easily achieved and internal drainage of heating fluid is obtained for all pipes and headers. The construction is designed for easy repair in the field if leaks OCCUR 1 Claim, 4 Drawing Figures PATENTEU AUG 51915 SHEET FIG.4

HEAT TRANSFER COIL BRIEF SUMMARY OF THE INVENTION This invention pertains to improvements in heat transfer coils. and more particularly to coils employed in bottle washers utilizing washing solutions of a caustic character.

Washing apparatus for containers or bottles is in tended to remove labels from the exterior and to cleanse the interior in preparation for reuse. The bottles are usually conveyed in pockets of a conveyor system that carry the bottles through several tanks containing caustic washing solution. The solution is very corrosive on metallic components, and in general the caustic is hign concentrations of sodium hydroxide, al kaline materials such as phosphates, polyphosphates, chelating agents and wetting agents.

In the washing apparatus, the washing solution is heated by heat transfer coils immersed in the washing solution. The heat, usually steam or hot water, increases the activity of the washing solution and helps sterilize the bottles. The environment for such coils, and they are usually embossed panel coils, is destruc tive in that pin holes develop along the grain bound aries where the metal has undergone embossing strain. The embossed sheets used to form panel coils undergo caustic embrittlement or intercrystalline cracking which is a form of corrosion characterized by cracking of the metal along the grain boundaries. The corrosion attack on the metal is usually in the areas of high concentrations of sodium hydroxide, as reported in Combustion Engineering by Otto de Lorenz (published in 1950). The solution to the problem of caustic embrittlement has been to use stress relieved panel coil sheets and to go to heavier gauge material, all of which has increased the cost beyond the reasonable level.

The heat transfer coil of this invention is constructed to approximate the compactness of panel coils, but to have the additional desirable features of low cost, extended life, and the capability of being repaired.

A preferred embodiment consists of a series of metal lic pipes arranged in stacked relation (one above the other) and formed at its ends with flattened portions which, when angularly oriented, allow the placement of securing means around the periphery to form a fluid tight joint between the ends of the pipes and the face sheet of the headers. The face sheets are easily formed with oblong slots to mate with the flattened shape of the pipe ends. The securing means is a welding bead which is capable of being placed completely around each pipe end even though the greater lengths of the pipes are juxtaposed to approximate a panel coil and thereby avoid collecting labels and foreign material brought into the washing solution on or in the bottles.

The advantages of the embodiment of this invention are that the pipes can be welded into the header face sheets to form a fluid tight joint, the flattened ends of the pipes provide for drainage of the fluid out of the pipes into the headers, and the shape of the exit of the coil facilitates the drainage of condensate so that water hammer is avoided and improved heat exchange is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The heat transfer coil of this invention is shown in a preferred embodiment on the following drawings which form a part of this specification, and in which:

FIG. 1 is a side elevational view of a preferred embodiment of the heat transfer coil;

FIG. 2 is a sectional view taken along the line 22 of FIG. 1',

FIG. 3 is an end view partly in section of the heat transfer coil taken along the line 33 in FIG. 1; and

FIG. 4 is a fragmentary and enlarged view ofa typical pipe of the heat transfer coil.

DETAILED DESCRIPTION OF THE HEAT TRANSFER COIL The preferred embodiment of the heat transfer coil, as seen in FIG. I and the other views of the drawings, includes one end header ]0 which provides a hollow interior chamber 11. One wall of the chamber 11 is constituted by a face sheet 12 in which there is formed a series of oblong slots to receive the end portions 13 of a plurality of pipes 14. The uppermost pipe 14A is somewhat smaller than the pipes therebelow and forms the connection for a plurality of coil supports 15. The lowermost pipe 148 is provided with a plurality of tie bars 16 which also provide support. As seen in FIG. I the righthand end of the pipes 14 and 14A are connected to a second header 17 which is formed with a chamber 18 and one wall of the chamber is a face sheet 19 formed with a series of oblong slots to receive the ends of the pipes 14. The uppermost pipe 14A is circu- Iar in section and therefore the connection of its end portions in the respective face sheets 12 and 19 is through a circular opening. The header 17 is provided with a heat transfer fluid inlet pipe 20 which opens into the upper end portions of the header I7 so as to direct the heat transfer fluid into all of the pipes and to the opposite header 10. There is an outlet pipe 21 of circular opening in the lower end of the face sheet 19, and its inner end 22 is connected in fluid tight relation to an outlet adaptor 23 which is suitably shaped to form the intermediate connection between the end 24 of the larger circular pipe 14B and the end 22 of the smaller pipe 21.

It is particularly shown in FIGS. 2, 3, and 4 that each of the pipes 14, and one end of the pipe 143 is circular throughout the greater portion of its length and at the respective ends these pipes are suitably shaped to form oblong ends 13 in which two opposite walls 13A are flattened so as to expand the pipe (FIG. 4) in one direction into a major dimension D which is perpendicular to the minor dimension as measured across the flat tened portions 13A. It has been previously explained that the respective face sheets I2 and 19 are each formed with oblong slots 25 so as to provide an opening of substantially the same shape as the end portions of the pipes 14 and MB. The result of shaping the end portions of the pipes is to assure the pipe end portions having a matching fit with the oblong slots of the face sheets. The attainment of the matching fit allows weld material 26 to be used to form fluid tight connections of the pipes to the slots 25 in the face sheets.

One of the important characteristics of the heat transfer coil is to arrange the components thereof so as to closely approximate a panel coil, thereby eliminating spaces between the respective pipes and avoiding the possibility of having labels and similar material collect between the pipes 14. Accordingly the coil assembly is arranged by having the major dimension of the oblong slots in the face sheets 12 and 19 turned to an angle A relative to the vertical stack of pipes 14 (see FIG. 3). The preferred angle from the vertical may be between 50 and 55 degrees, and when this angular arrangement is followed certain advantages accrue. For example, the major length of the pipes 14 can be brought to abutment or nearly in abutment so as to gain the advantage of a panel coil. In addition, with the flattened oblong ends 13 of the respective pipes 14 turned so as to fit into the oblong slots 25, it is possible to obtain a complete water tight weld 26 around each pipe end portion and the adjacent face sheet. Without shaping the pipe end portions as described it would be impossible to ef fectively obtain a water tight weld completely around each individual pipe. There is another advantage to obtained from the similar orientation of the oblong pipe ends and the face sheet slots and that is that the oblong shape and the angular orientation of the pipes allow the drainage of condensate into the respective headers at the internal sloped portion 27 (FIG. 3) so that substantially all of the condensate can be drained from the coil, except the possibility of some condensate collecting at the bottom space 18A of the header chamber 18.

Heat transfer coils normally used in bottle washers must have a design to permit installation in very limited spaces, so that compactness is important. The heat transfer coils are located in compartments of a bottle washer to raise the temperature of the caustic washing solution and therefore are subject to fouling from paper labels, pulp, scale, and broken glass. Hence, it is critical to the coil configuration that it should present a smooth heat transfer surface so as to minimize fouling which reduces the effectiveness of heat transfer and allows easier cleaning merely by washing with a stream of water from a hose.

It has been found that embossed panel coils have an extremely short service life because of caustic embrittlement which causes pin holes to develop along the lines where the panel sheets have been embossed in order to form the internal fluid passages. One solution to the short life experience uses panel coils has been to stress relieve the embossed panels and to use heavier gauged material. Both of these solutions add to the cost and such costs are considered to be excessive. The heat transfer coil of the present invention is considerably less expensive than applying the solutions to the continued use of panel coils, and all of the advantages present in panel coils can be retained along with the advantages that have been enumerated above. It is also possible with the embodiment of the heat transfer coil herein described to effect field repair if a pipe should develop a leak. All that is required is to remove the weld 26 at the ends of the leaking pipe and to insert a replacement pipe and reweld the end portions. It should be pointed out that the free drain provided by the shaping of the end portions of the pipes I4 avoids the collection of condensate which causes destructive water hammer and also reduces heat transfer.

It is believed that the foregoing detailed description has indicated the uniqueness of the construction, and the advantages set forth are believed to be readily understood.

What is claimed is:

I. In a heated fluid carrying coil construction for container washers using caustic washing solution in which the coil is emersed to heat the caustic solution, the improvement which consists in spaced elongated headers each having a face sheet formed with a plurality of oblong apertures having the major dimensions thereof oriented at substantially the same angle of to to the elongation of said header face sheets, fluid conducting pipes extending between said header face sheets, each pipe having a round body and fluid drain facilitating end portions flattened to an oblong shape for fitting into said face sheet oblong apertures, said angle of orientation of the oblong apertures placing said round bodies of said pipes in abutment throughout substantially the full length thereof between said end portions to block the free flow of the washing solution therebetween, and welding means applied around said flattened end portions of said pipes to secure said end portions into said face sheets and form a fluid seal head around the periphery of each oblong end portion, means to supply a heated fluid into one pipe for flooding said pipes and headers, and means connected to one header to discharge the heating fluid. 

1. In a heated fluid carrying coil construction for container washers using caustic washing solution in which the coil is emersed to heat the caustic solution, the improvement which consists in spaced elongated headers each having a face sheet formed with a plurality of oblong apertures having the major dimensions thereof oriented at substantially the same angle of 50* to 55* to the elongation of said header face sheets, fluid conducting pipes extending between said header face sheets, each pipe having a round body and fluid drain facilitating end portions flattened to an oblong shape for fitting into said face sheet oblong apertures, said angle of orientation of the oblong apertures placing said round bodies of said pipes in abutment throughout substantially the full length thereof between said end portions to block the free flow of the washing solution therebetween, and welding means applied around said flattened end portions of said pipes to secure said end portions into said face sheets and form a fluid seal bead around the periphery of each oblong end portion, means to supply a heaTed fluid into one pipe for flooding said pipes and headers, and means connected to one header to discharge the heating fluid. 